1. Field of the Invention
The present invention relates to a display panel using organic electroluminescence-devices (hereafter referred to as organic EL devices) and a method of manufacturing the display panel, and more particularly to an organic EL color display panel having light emitting portions in a plurality of luminous colors and to a method of manufacturing the organic EL color display panel.
2. Description of the Related Art
There have been disclosed conventional organic EL display panels, for example, in JP-A 8-315981, 10-312886 and 11-194585.
In such organic EL display panels, during the process of making an organic EL display panel, it is generally difficult to pattern organic EL medium layers or electrode layers after forming the organic EL medium layers because of low heat resistance, low solvent resistance and low humidity resistance of the organic EL medium used in charge injection layers and light emitting layers. For example, when the photolithography generally used to pattern thin films is used for the patterning in the organic EL display panel, a problem arises that the organic
EL device characteristics are degraded by infiltration of solvent into photoresist, by a high-temperature ambient gas during baking of photoresist, by infiltration of photoresist development liquid into the devices, or by damages to devices by plasma during dry etching.
Other examples of the patterning method include a vapor deposition method that uses a mask to pattern the organic EL medium layers and electrode layers. However, because of the wraparound of vapor that may occur in gaps between the mask and the substrate and the shadowing caused by projections and debris, the coverage of the organic EL medium may become insufficient. This in turn causes characteristic degradations during the operation of the organic EL display panel, such as current leakage and poor emission of light, which stand in the way of performance enhancement of the organic EL display panel.
Also, in the conventional full color organic EL display panel, when the same organic EL material is used commonly for the organic EL medium layers of different luminous colors, the layers are formed under the same conditions irrespective of the colors. Hence, the light emitting characteristics of the individual light emitting portions cannot be optimized according to the colors, which is detrimental to enhancing the performance of the full color organic EL display panel.